/**
 *  判断经纬度是否超出中国境内
 */
function isLocationOutOfChina(latitude, longitude) {
	if (longitude < 72.004 || longitude > 137.8347 || latitude < 0.8293 || latitude > 55.8271)
		return true;
	return false;
}


/**
 *  将WGS-84(国际标准)转为GCJ-02(火星坐标):
 */
function transformFromWGSToGCJ(latitude, longitude) {
	var lat = "";
	var lon = "";
	var ee = 0.00669342162296594323;
	var a = 6378245.0;
	var pi = 3.14159265358979324;

	if (isLocationOutOfChina(latitude, longitude)) {
		lat = latitude;
		lon = longitude;
	}
	else {
		var adjustLat = transformLatWithXY(longitude - 105.0, latitude - 35.0);
		var adjustLon = transformLonWithXY(longitude - 105.0, latitude - 35.0);
		var radLat = latitude / 180.0 * pi;
		var magic = Math.sin(radLat);
		magic = 1 - ee * magic * magic;
		var sqrtMagic = Math.sqrt(magic);
		adjustLat = (adjustLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
		adjustLon = (adjustLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
		latitude = latitude + adjustLat;
		longitude = longitude + adjustLon;
	}
	return { latitude: latitude, longitude: longitude };

}

/**
 *  将GCJ-02(火星坐标)转为百度坐标:
 */
function transformFromGCJToBaidu(latitude, longitude) {
	var pi = 3.14159265358979324 * 3000.0 / 180.0;

	var z = Math.sqrt(longitude * longitude + latitude * latitude) + 0.00002 * Math.sin(latitude * pi);
	var theta = Math.atan2(latitude, longitude) + 0.000003 * Math.cos(longitude * pi);
	var a_latitude = (z * Math.sin(theta) + 0.006);
	var a_longitude = (z * Math.cos(theta) + 0.0065);

	return { latitude: a_latitude, longitude: a_longitude };
}

/**
 *  将百度坐标转为GCJ-02(火星坐标):
 */
function transformFromBaiduToGCJ(latitude, longitude) {
	var xPi = 3.14159265358979323846264338327950288 * 3000.0 / 180.0;

	var x = longitude - 0.0065;
	var y = latitude - 0.006;
	var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * xPi);
	var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * xPi);
	var a_latitude = z * Math.sin(theta);
	var a_longitude = z * Math.cos(theta);

	return { latitude: a_latitude, longitude: a_longitude };
}

/**
 *  将GCJ-02(火星坐标)转为WGS-84:
 */
function transformFromGCJToWGS(latitude, longitude) {
	var threshold = 0.00001;

	// The boundary
	var minLat = latitude - 0.5;
	var maxLat = latitude + 0.5;
	var minLng = longitude - 0.5;
	var maxLng = longitude + 0.5;

	var delta = 1;
	var maxIteration = 30;

	while (true) {
		var leftBottom = transformFromWGSToGCJ(minLat, minLng);
		var rightBottom = transformFromWGSToGCJ(minLat, maxLng);
		var leftUp = transformFromWGSToGCJ(maxLat, minLng);
		var midPoint = transformFromWGSToGCJ((minLat + maxLat) / 2, (minLng + maxLng) / 2);
		delta = Math.abs(midPoint.latitude - latitude) + Math.abs(midPoint.longitude - longitude);

		if (maxIteration-- <= 0 || delta <= threshold) {
			return { latitude: (minLat + maxLat) / 2, longitude: (minLng + maxLng) / 2 };
		}

		if (isContains({ latitude: latitude, longitude: longitude }, leftBottom, midPoint)) {
			maxLat = (minLat + maxLat) / 2;
			maxLng = (minLng + maxLng) / 2;
		}
		else if (isContains({ latitude: latitude, longitude: longitude }, rightBottom, midPoint)) {
			maxLat = (minLat + maxLat) / 2;
			minLng = (minLng + maxLng) / 2;
		}
		else if (isContains({ latitude: latitude, longitude: longitude }, leftUp, midPoint)) {
			minLat = (minLat + maxLat) / 2;
			maxLng = (minLng + maxLng) / 2;
		}
		else {
			minLat = (minLat + maxLat) / 2;
			minLng = (minLng + maxLng) / 2;
		}
	}

}

function isContains(point, p1, p2) {
	return (point.latitude >= Math.min(p1.latitude, p2.latitude) && point.latitude <= Math.max(p1.latitude, p2.latitude)) && (point.longitude >= Math.min(p1.longitude, p2.longitude) && point.longitude <= Math.max(p1.longitude, p2.longitude));
}

function transformLatWithXY(x, y) {
	var pi = 3.14159265358979324;
	var lat = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
	lat += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	lat += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
	lat += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
	return lat;
}

function transformLonWithXY(x, y) {
	var pi = 3.14159265358979324;
	var lon = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
	lon += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	lon += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
	lon += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
	return lon;
}

// 百度坐标系转大地坐标系
    function BD09II2WGS84(bdLon, bdLat) {
		let x_pi = 3.14159265358979324 * 3000.0 / 180.0;
		//百度坐标转成火星坐标
		let mars_point = { lat: 0, lon: 0,};
		let x = bdLon - 0.0065;
		let y = bdLat - 0.006;
		let z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * x_pi);
		let theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * x_pi);
		mars_point.lat = z * Math.sin(theta);
		mars_point.lon = z * Math.cos(theta);
 
		//把火星坐标GCJ02转地球坐标系WGS84
		let gcjLat =  mars_point.lat;
		let gcjLon = mars_point.lon;
		let d = delta(gcjLat, gcjLon)
		return {
			'lat': ( gcjLat - d.lat ),
			'lon': ( gcjLon - d.lon )
		}
	}
	function delta(lat, lon) {
		let PI = 3.14159265358979324;
		let a = 6378245.0 
		let ee = 0.00669342162296594323 
		let dLat = transformLat(lon - 105.0, lat - 35.0)
		let dLon = transformLon(lon - 105.0, lat - 35.0)
		let radLat = lat / 180.0 * PI
		let magic = Math.sin(radLat)
		magic = 1 - ee * magic * magic
		let sqrtMagic = Math.sqrt(magic)
		dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * PI)
		dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * PI)
		return {
			'lat': dLat,
			'lon': dLon
		}
	}
	function transformLat(x, y) {
		let PI = 3.14159265358979324;
		let ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x))
		ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0
		ret += (20.0 * Math.sin(y * PI) + 40.0 * Math.sin(y / 3.0 * PI)) * 2.0 / 3.0
		ret += (160.0 * Math.sin(y / 12.0 * PI) + 320 * Math.sin(y * PI / 30.0)) * 2.0 / 3.0
		return ret
	}
	function transformLon(x, y) {
		let PI = 3.14159265358979324;
		let ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x))
		ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0
		ret += (20.0 * Math.sin(x * PI) + 40.0 * Math.sin(x / 3.0 * PI)) * 2.0 / 3.0
		ret += (150.0 * Math.sin(x / 12.0 * PI) + 300.0 * Math.sin(x / 30.0 * PI)) * 2.0 / 3.0
		return ret
	}

module.exports = {
	isLocationOutOfChina: isLocationOutOfChina,
	transformFromWGSToGCJ: transformFromWGSToGCJ,
	transformFromGCJToBaidu: transformFromGCJToBaidu,
	transformFromBaiduToGCJ: transformFromBaiduToGCJ,
	transformFromGCJToWGS: transformFromGCJToWGS,
    BD09II2WGS84
}
